steep tank holding up to25,000 bushels, where it soaks in circulating water, maintainedat 125 and sligLDly acidifiedwith 0.1 to 0.2 percent of sulfur dioxide. Steeping the cornfor 24 to 48 hours softens thekernel, loosens the hull and germ and swells the endosperm. Steeping takes placein a series of tanks, which are operated in a continuous batchprocess.

The water circulatescounter currently through the tanks, so when it is finally with drawn from the newest batch,

ithas a relatively high concentration of soluble. The steepingprocess facilitates separation ofthe components of the kerneland loosens the gluten bonds torelease the starch. Dischargedsteepwater, rich in protein at 35to 45 percent of total solids, isconcentrated in vacuum evaporators to a solids content of 35to 55 percent. Steepwater concentrate is utilized in feed products or in industrial fermentationmedia.

Softened corn from the steeptanks is coarsely ground withwater in an attrition mill tofree the hull, the germ and alarge portion of the flouryendosperm starch and gluten.The slurry of coarsely groundcorn is forced under pressureinto hydro cyclone, which centrifugally separate the ligLDercorn germ, which is then carried off to washing screens.Washed germ is conveyed to aLD and from there to oilrecovery facilities. Washingsfrom the germ are piped tothe starch centrifuges. Heavyfractions from the coarsegrinding mills and germ separators are passed through finegrinding mills and washingscreens

for fiber separation.Finally, the slurry is sent tocentrifuges for separation ofgluten (ligLD phase) fromstarch (heavy phase).

The gluten fraction passes to acentrifugal concentrator and isfiltered and dried. The starch stream goes to washing cyclones fed with fresh water;overflow, containing residualgluten from the Â¡Â°mill starch, is recycled to the starch centrifuge; underflow from thewashing cyclones, a suspension of starch containing onlyabout 0.3 percent protein, ispassed through a

Degummingremoves phosphatides andother materials that may beprecipitated or dissolved fromthe crude oil by hot water.This step is usually omitted inrefineries that process onlycorn oil, but is used in refineries that are set up to refinesoybean oil as well as corn oil.Degumming is accomplishedby introducing hot water at alevel of 1 to 3 percent of oilvolume, or by injecting anequivalent amount of steamto hydrate the phosphatides.The phosphatides, togetherwith certain other materials, absorb water and precipitatefrom the oil as a heavierphase, which is removed bycentrifugation.

When degumming is omitted,the refiner depends on an alkalirefining step, which uses roughly the same temperatureas a degumming operation, totake out the phosphatides along with the free fatty acids(in the form of soapstock) andto reduce color. Phospholipids, corn lecithin, can berecovered from both degumming and alkali refining residues.

In the alkali refining step, freefatty acids are neutralized bytreatment at 82- 100 degree with a small amount ofconcentrated sodium hydroxide solution. Alkali refiningreduces color and also removesother nontriglyceride substances, which are separatedalong with the neutralized freefatty acids and hydrated phosphatides, by centrifugation.The alkali treated oil is usuallywashed with a small quantityof hot water to remove residual soap formed by thealkali treatment. The separatedresidues from alkali treatmentare sold as soapstock or acidulated soapstock, which contains about 95 percent freefatty acids.

Bleaching The oil is then decolorized bytreatment with acidactivatedclays that bleach by LDorbingcolor bodies, residual soapsand metal complexes from theoil. In plants producing partially hydrogenated oil alongwith regular corn oil, bleachedoil coming from the filter ispiped to the hydrogenationvessel. When that process iscompleted, the partially hydrogenated oil is passed througha filter to remove catalystparticles and other extraneousmaterial. Further bleaching,deodorization and filtrationyield a clear, pale yellow oil.

Refining of the unmodifiedoil continues with winterization. Waxes, present in the oilin small amounts characteristically have high melting pointsand are readily crystallized bychilling in refrigerated vessels.They are then removed byfiltration. This produces ahaze-free finished oil whenrefrigerated.

Finally, deodorization is accomplished by a continuoussteam distillation under highvacuum at high temperature232-260 degree Oil is fed into the top of thedistillation tower, while a jetof steam entering at the basecarries the volatile odorantswith it as it passes upwardsand exits near the top. Condensed exhaust steam contains odor, color, flavor components and the remainingtraces of free fatty acids. Thedeodorized oil is drawn off atthe bottom of the tower, thendried and passed through apolish filter to become thefinal product, refined corn oil.

We believe that whatever the field is, quality has always been at the heart of the company’s performance. We treat quality and service as a way of life and hope to serve you in the best possible manner on a long term and mutually beneficial basis. If you want to know more information please contact us. Our responsible, experienced technical team is always ready to serve and guide you at any time.

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